Systems wherein a stack of articles or goods upon a pallet can be packaged by wrapping a foil around therein substantially horizontally in a generally spiral pattern or in annular sections so that the foil will extend around the vertical sides of the palletized unit are, of course, known. The foil bands which are used are generally so called stretch foils which are already prestretched and thus have been strengthened by a stretching process.
The apparatus for applying such foil wraps can comprise a substantially toroidal frame which is vertically displaceable and carries a support ring which can extend in a horizontal plane. A rotating ring can be driven about a vertical axis on the support ring and can carry a satellite provided with means for receiving a roll of the foil band and a means for braking the delivery of the foil from that roll.
For the winding operation, the support frame is initially lowered to its bottom-most position and a free end of the foil band is applied to the stack. The satellite is then caused to orbit the stack as the support frame is gradually raised so that, as the satellite orbits the stack in a generally helical pattern, the foil band will be wrapped around the vertical sides of the stack and, because the delivery of the foil is braked, an additional stretch will be applied to the foil which thus engages the stack of articles under tension.
To avoid shifting of the articles of the stack it is also known to provide a fixing plate on the apparatus which can be lowered onto the top of the stack to hold the articles in place as the foil is wrapped therearound.
Furthermore, a cover sheet applying device can be provided which can overhang the top of the palletized unit in an outrigger fashion to apply a foil sheet to the stack which can be held in place by the last turns of the foil band.
A drawback of this wrapping method is that it does not always ensure a good connection between the stack of articles and the pallet. Furthermore, the wrapping system does not provide a residual vertical force on the stack which can assist in holding the articles against one another and against the pallet.
It is also known to wrap palletized units with substantially vertical turns of foil which pass over the head and under the foot of the unit and also, therefore, are wound around the vertical sides thereof. After winding the palletized unit in the vertical direction along two vertical sides, the unit is rotated through 90.degree. about its vertical axis and the foil wrap is then applied in a direction crosswise to the first direction, also in the vertical sense so that all six sides of the unit will be wrapped.
In this method, a vertical stress is applied to the stack of articles to hold the stack against the pallet and the articles of the stack against one another. However, in this case, the positioning of the articles in the horizontal direction is not always satisfactory. Indeed, horizontal shifting of the articles frequently cannot be avoided.
Furthermore, this latter method results in winding of the foil wrap around the skids of the pallet so that frequently the packaged unit cannot be transported by means of a manually operated lift or, for that matter, a mechanically driven forklift. In transportation of the palletized wrapped unit there is always the danger that the foil segments in the region of the skids will be damaged or ruptured and hence the connection of the stack of articles to the pallet will be weakened or broken.